In our task, the ratio between the background and the smallest organ can reach around \(10^{5}:1\) , which makes the loss function values dominated by large numbers of easy background voxels. To solve this problem, we first use the exponential logarithmic loss [1]} \((L_{Exp})\) , which balances the labels not only by their relative sizes but also by their segmentation difficulties:
\(L_{Exp} = \omega _{DSC}L_{DSC} + \omega _{Cross}L_{Cross}\) 
